CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF THE CLASS ALPHA-1,2-MANNOSIDASE FROM SACCHAROMYCES-CEREVISIAE

The alpha 1,2-mannosidase from Saccharomyces cerevisiae catalyzes the conversion of Man(9)GlcNAc(2) to Man(8)GlcNAc(2) during the formation of N-linked oligosaccharides and is a member of the Class 1 alpha 1,2- mannosidases conserved from yeast to mammals. The enzyme is a type II membrane protein and a recombinant form of the alpha 1,2-mannosidase f rom S. cerevisiae, lacking the transmembrane domain, has been expresse d in Pichia pastoris and crystallized using the hanging drop vapor dif fusion technique, The crystals grow as flat plates, with unit cell dim ensions a = 57.5 Angstrom, b = 84.1 Angstrom, c = 107.1 Angstrom, alph a = beta = gamma = 90 degrees. The crystals exhibit the symmetry of sp ace group P2(1)2(1)2(1) and diffract to a minimum d-spacing of 3.5 Ang strom resolution. On the basis of density calculations one monomer is estimated to be present in the asymmetric unit (V-m = 2.08 Angstrom(3) Da(-1)). This is the first report of the crystallization of any glyco sidase involved in N-glycan biosynthesis. (C) 1997 Academic Press.